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Trouble measuring voltage across a resistor with scope

Question asked by geek4ever on May 22, 2008
Latest reply on May 23, 2008 by dnt
Hi,

I need help troubleshooting something. I am tying to measure the power consumption of a wireless card. I have a pcmcia extender circuit which gives me access to the required pins.

To measure current (to get power eventually) I want to measure voltage across a series resistor (1 ohm or so). But in my circuit. how do I use the scope probes to measure voltage across a resistor? If I connect the scope probe to one side of the resistor and ground pin to the other side of resistor, the circuit seems to disconnect with the wireless card not getting any power. So how should the probe be connected to measure voltage across this resistor?

I can measure voltage across the resistor with a simple multimeter (obviously with low smapling frequency). This indicates the circuit is setup right. Its just that connecting the scope probe doesnt not work as above. Any ideas? I am a relative newbie to circuits and measurements.

Thanks,
Vin  

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